The present invention relates generally to an electromagnetic relay, and more particularly to a compact electromagnetic relay mounted on a circuit board.
In the prior art, Japanese Patent Application Kokoku No. H4-42766 describes a conventional electromagnetic relay, which is shown in FIG. 5.
The electromagnetic relay comprises an insulating base housing 110, a contact part 120, an operating electromagnet 130 and a case 140.
The base housing 110 is formed with wall members 115 and 116 protruding on both ends of a substantially rectangular body extending in a longitudinal direction, and includes insertion holes 111 and 112 formed in the front sides of the respective wall members 115 and 116 (toward the front in FIG. 5). Insertion parts 131a (only one insertion part 131a is shown in FIG. 5) on a gate-form iron core 131 are each press-fitted into a respective one of the insertion holes 111, 112. A circular receiving hole 113 is formed in close proximity to a corner of the insertion hole 111 on the side of the wall member 115 and receives a leg 133d of an armature 133. In addition, a receiving groove 114 is formed in close proximity to a corner of the insertion hole 112 on the side of the wall member 116 and receives a protrusion 133f of the armature 133 and regulates the pivoting range of the armature 133. A pair of through-holes 117 are formed in the wall member 116 and allow the passage of coil terminals 135.
The contact part 120 comprises a fixed contact 121 and a movable contact 123. The fixed contact 121 and movable contact 123 have a fixed contact point 122 and a movable contact point 124, respectively, on facing surfaces, and have board connecting portions (not shown) connected to a circuit board (not shown). The fixed contact 121 and movable contact 123 are formed by stamping and forming copper alloy plates consisting of phosphorus bronze, etc., and are fastened to the wall member 115 of the base housing 110.
The operating electromagnet 130 comprises a gate-form iron core 131, a winding frame 132 fastened to the gate-form iron core 131 by press-fitting, an armature 133, and an excitation coil 134.
The gate-form iron core 131 is formed in the shape of a gate-form flat plate with a body (not shown) extending in the horizontal direction and a pair of legs 131b (only one leg 131b is shown) extending downward from both ends of the body. The core 131 is formed by stamping an iron core. Insertion parts 131a, press-fitted in the insertion holes 111 and 112, protrude from the lower ends of the legs 131b of the gate-form iron core 131. A projection 131c is formed on an upper portion of one end of the gate-form iron core 131.
The winding frame 132 comprises a winding body (not shown) with a U-shaped cross section which extends in the horizontal direction and which has a U-shaped groove open at the top, flanges 132a arranged on both ends of the winding body, and a terminal 132b which extends to one side as a continuation of one of the flanges 132a. The winding frame 132 is formed by molding an insulating synthetic resin. The body of the gate-form iron core 131 is press-fitted in the U-shaped groove of the winding body of the winding frame 132, so that the gate-form iron core 131 and the winding frame 132 are formed into an integral unit. Two coil terminals 135 are fastened to the terminal 132b. The excitation coil 134 is wound around the circumference of the winding body of the winding frame 132, and the ends of the excitation coil 134 are connected to a respective one of the coil terminals 135.
The armature 133 is constructed with an inverted gate shape by stamping an iron plate, and comprises a horizontal portion 133a extending in the horizontal direction, and a pair of vertical portions 133b and 133c extending upward from both ends of the horizontal portion 133a. A leg 133d acts as a support for the armature 133 and protrudes from a lower end of the vertical portion 133b on one end of the armature 133. A protrusion 133f, used to regulate the pivoting range of the armature 133, protrude from the lower end of the vertical portion 133c on the other end of the armature 133. A recess 133e, mated with the projection 131c of the gate-form core 131, is formed in the upper end of the vertical portion 133b on one end of the armature 133 on the axial line of the leg 133d. An insulating operating part 133g is mounted on the horizontal portion 133a of the armature 133.
The operating electromagnet 130, constructed as described above, is installed on the base housing 110 by press-fitting both insertion parts 131a of the gate-form iron core 131 in the insertion holes 111 and 112, inserting the leg 133d of the armature 133 into the receiving hole 113 of the base housing 110, and inserting the protrusion 133f into the receiving groove 114. At the same time, the coil terminals 135 are passed through the through-holes 117 in the base housing 110. In this manner, the leg 133d is supported in the receiving hole 113, and the recess 133e on the axial line of the leg 133dengages with the projection 131c. In view of this assembly, the armature 133 can pivot about the leg 133d and the recess 133e on the axial line of the leg 133d. The armature 133 receives a spring force via the operating part 133g from the movable contact 123, which also acts as a return spring, so that in the non-excited state of the excitation coil 134, the vertical portion 133c on the second end of the armature 133 is separated from the gate-form iron core 131. On the other hand, when the excitation coil 134 is excited, the vertical portion 133c on the second end of the armature 133 pivots about the leg 133d and the recess 133e located on the axial line of the leg 133d, and is caused to adhere to the gate-form iron core 131. As a result, the movable contact 123 is pressed so that it undergoes elastic deformation, thus causing the contact points 122 and 124 to close.
The case 140 is a substantially rectangular member with an accommodating space (not shown) formed inside that covers the base housing 110 and the operating electromagnet 130 installed on the base housing 110. The case 140 covers the base housing 110 and operating electromagnet 130, and is anchored to the base housing 110. A projection (not shown) is arranged in the accommodating space of the case 140 to press against the upper end on the side of the projection 131c of the gate-form iron core 131 and another projection (not shown) is arranged in the accommodating space to prevent the upper end of the vertical portion 133b on the pivoting fulcrum side (first end) of the armature 133 from tilting when the base housing 110 and operating electromagnet 130 are covered.
The electromagnetic relay constructed as described above provides an ultra-compact magnetic relay inexpensively and with high productivity.
Another conventional electromagnetic relay is shown in FIG. 6 and is described more fully in Japanese Patent Application Kokai No. 2001-68003. The basic structure of the electromagnetic relay is similar to that of the relay shown in FIG. 5 (the electromagnetic relay of Japanese Patent Application Kokoku No. H4-42766). Specifically, an armature 212 is arranged along a gate-form iron core 211 fastened to a base housing 210. The armature 212 is formed with an inverted gate shape by stamping an iron plate. A shaft 213 acts as a pivoting center and is arranged on a lower end of one side of the armature 212, and a protrusion 214 of the armature 212 is arranged on a lower end of the other side of the armature 212. The shaft 213 of the armature 212 is inserted into a shaft receiving hole 215 formed in the base housing 210, and the protrusion 214 is inserted into a receiving hole 216 formed in the base housing 210 so that the protrusion 214 is capable of movement. A recess (not shown) similar to the recess 133e shown in FIG. 5, is formed in the upper end of the side of the armature 212 that acts as the pivoting center, on the axial line of the shaft 213. The recess mates with a projection (not shown) formed on the upper portion of one side of the gate-form iron core 211, and forms a pivoting center for the armature 212 together with the shaft 213. A wide portion 218 is formed in the corner of the L-shaped insulating wall 217 of the base housing 210, and the opening-and-closing stroke S of the armature 212 is regulated by causing the corner at the second end of the armature 212 to contact the wide portion 218 of the insulating wall 217. Reference numeral 219 designates a fixed contact, and reference numeral 220 designates a movable contact.
The electromagnetic relay of Japanese Patent Application Kokai No. 2001-68003 has a high operating reliability, and moreover, the opening-and-closing stroke S of the armature 212 is stabilized in a limiting design, and the opening-and-closing operating force and load force are fixed.
However, the following problems have been encountered in these conventional electromagnetic relays.
In the electromagnetic relay shown in FIG. 5 (that of Japanese Patent Application Kokoku No. H4-42766), the armature 133 can pivot about the leg 133d and the recess 133e located on the axial line of the leg 133d as a result of the leg 133d being supported in the receiving hole 113 and the recess 133e located on the axial line of the leg 133d being supported on the projection 131c. Since the movement of the leg 133d in the horizontal direction of the armature 133 (the left-right direction in FIG. 5) and in the forward-rearward direction perpendicular to the horizontal direction can be regulated, the support of the leg 133d by the receiving hole 113 does not become unstable. At the same time, the engagement of the recess 133e with the projection 131c is arranged so that the movement of the recess 133e in the horizontal direction of the armature 133 can be regulated. However, since the movement of the recess 133e in the forward-rearward direction perpendicular to the horizontal direction cannot be regulated, this support is unstable. In order to stabilize the support of the recess 133e in the forward-rearward direction, a projection that prevents the tilting of the upper end of the vertical portion 133b on the side of the pivoting fulcrum of the armature 133 is arranged in the accommodating space of the case 140. It is a problem however that, since the case 140 that covers the operating electromagnet 130 and the base housing 110 is relatively large, the dimensional error in the product at the time of molding is large, so that the dimensional error in the above-mentioned projection formed in the accommodating space for the base housing 110 is also inevitably large. As a result, the support of the above-mentioned recess 133e in the forward-rearward direction is inevitably unstable because of the dimensional error in the projection and base housing 110. Accordingly, the pivoting axis of the armature 133 is unstable, so that there is a risk that the movement of the armature 133 will not be smooth.
Furthermore, in the case of the electromagnetic relay shown in FIG. 6 (that of Japanese Patent Application Kokai No. 2001-68003), the support in the forward-rearward direction of the recess that constitutes the pivoting center of the armature 212 is unstable. Accordingly, the pivoting axis of the armature 212 is unstable so that there is a risk that the movement of the armature 212 will not be smooth.
Accordingly, it is an object of the present invention to provide an electromagnetic relay which avoids the above-mentioned problems of the prior art electromagnetic relays and in which the pivoting of an armature is not affected by dimensional error or deformation of the case or base housing, so that the armature can pivot smoothly.
An electromagnetic relay in accordance with the invention comprises a substantially C-shaped flat-plate-form yoke which has a body extending in a horizontal direction and first and second legs extending downward from both ends of the body, and an insulating winding frame which has a winding body attached to the body of the C-shaped flat-plate-form yoke, and which has an excitation coil wound around the circumference of the winding body. The electromagnetic relay also includes an armature having a horizontal portion which extends in the horizontal direction, and on which an insulating operating part is arranged, a pivoting shaft extending from one end of the horizontal portion in the direction of extension of the first leg, and a vertical portion which extends from the other end of the horizontal portion, and which contacts the second leg when the excitation coil is excited. An insulating base housing supports both of the first and second legs of the yoke, and has a recess or hole that receives a shaft portion formed on the lower end of the pivoting shaft of the armature. A movable contact and a fixed contact are attached to the base housing and contact each other as a result of the pressing of the operating part. The base housing has a protrusion extending upward in the vicinity of the first leg. The winding frame comprises an extension which extends toward the first leg from the winding body, and which has an upper portion positioned at least partially above the first leg. A recess is formed in the upper portion of the winding frame and extends parallel to the direction of extension of the body. The armature has a projection which protrudes upward on the upper end of the pivoting shaft, and the projection of the armature is arranged inside a space defined by the recess of the winding frame and the protrusion of the base housing.
As used herein, the term xe2x80x9csubstantially C-shapedxe2x80x9d includes shapes having corners.